Mitochondrial Genomics and Northwestern Atlantic Population Genetics of Marine Annelids

Robert M. Jennings, Ph.D., 2005 Lauren Mullineaux, Advisor

The overarching goal of this thesis was to investigate marine benthic annelid phylogenetics and population genetics. At the phylogenetic level, the whole mitochondrial genome sequencing of two polychaetes I performed supports recent revisions placing leeches and oligochaetes within the polychaete radiation. This re-interpretation also lends support to the inclusion of echiurids and siboglinids within annelids, and sipunculans as close allies. I then conducted a population genetics study on populations of Clymenella torquata from the Bay of Fundy to New Jersey to investigate a hypothesis that Cape Cod, MA is a barrier to gene flow. A barrier was found, but displaced south of Cape Cod. A gradient in genetic diversity was also found and is presumably due to glaciation. Finally, I constructed a population genetics model including a typical benthic invertebrate life cycle, and described the patterns of genetic differentiation at the juvenile and adult stages. Model analysis indicates that selection operating after settlement may be important in structuring genetic differentiation between populations and life stages. Further, it demonstrates how combined genetic analysis of sub-adult and adult samples can provide more information about population dynamics than either could alone.